This invention is directed to waveguide array systems, in general, and to dual-band, wideband, shared aperture waveguide systems, in particular.
There are many known methods, devices and systems associated with waveguide systems in general, and radar systems, in particular. For the most part, the known systems and devices are directed to single band arrays which operate on only one frequency signal at a time. These signals may be in the microwave frequency range, e.g., 3.5 GH.sub.z or the like. Typically, the known systems are of a relatively narrow scan capability.
Many of these systems include waveguide devices which are utilized with coaxial cables as the input or output means. In these types of systems, various types of transition devices are used to couple the waveguide to the cable.
In most cases the radar systems include a single band device. That is, the system operates on only one frequency band. Thus, two (or more) array apertures are required in order to process multiple frequencies. In the past, this has caused the multi-frequency systems to have multiple apertures with the attendant increases in cost, weight, size and the like. Thus, these systems have been disadvantageous for utilization in many applications.
Also, in the past, attempts have been made to provide systems wherein a single aperture has been shared by multiple antenna arrays. However, these prior systems were generally of poor quality due to interference and crosscoupling. The best known example of this technique was a twin-dielectric-slab-loaded waveguide array with each frequency band fed by a separate feeding probe as described by Mailloux et al (see Information Disclosure Statement). However, the two signal bands are difficult to isolate and the impedance matching is difficult resulting in relatively high VSWR, e.g. 3:1 or greater.